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89 Cards in this Set
- Front
- Back
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What is sterilization
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estruction of all forms of microbes--cells, endospores and viruses
but, not necessarily destruction of toxins (proteins) |
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Sterilization is the destruction of all forms of microbes. Name three microbes
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cells, endospores, and viruses
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Sometimes, sterilization does not destruct _____
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toxins (proteins)
if have bacterium with toxin, even though kill it, parts (toxins) may still be around |
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What is disinfection?
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killing, inhibition, or removal of pathogens from inanimate objects. Disinfectants can be phyical (UV, heat) or chemical (lysol)
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Disinfection is the killing, inhibition, or removal of pathogens from ______
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inanimate objects
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Antisepsis is the destruction of pathogens on _____
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living tissue
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Antiseptics (which carry out antisepsis) are almost always ____
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chemical
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What is sanitization?
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Reduction of microbial populations to levels safe according to public health standards
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What are four factors to determining the effectiveness of an antimicrobial agent?
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population size
population composition exposure time local environment |
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In population composition, microorganisms differ in _______
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their sensitivity to various agents
Mycobacterium tuberculosis has mycolic acid in cell wall. Because Mycobacterium tuberculosis has mycolic acid in it, it is harder to get rid of compared to E. coli |
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_______ has mycolic acid in cell wall. Because it has mycolic acid in it, it is harder to get rid of compared to E. coli.
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Mycobacterium tuberculosis
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Mycobacterium tuberculosis has ______ in the cell wall
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mycolic acid
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With exposure time, the _____ exposure, the more microbes killed
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longer
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A _____ pH makes heat more effective
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low (acidic environment)
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_____ can protect pathogens
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organic matter
(organic matter on top of pathogens make it hard to kill) |
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What are the two factors under local environment that determine the effectiveness of an antimicrobial agent?
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- low pH makes heat more effective
- organic matter can protect pathogens |
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A microbe is dead when it ____
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cannot grow anymore
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death of a microbial population is _____
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exponential
(example of death rate: 90% every minute) |
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Name three mechanisms of death
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- alteration of membrane permeability
- damage to proteins and nucleic acids - removal of water |
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altering membrane permeability could lead to death. Membrane damage causes _______, affects cell growth
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cell leakage
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damage to proteins and nucleic acids leads to death. Brakage of DNA or denaturation of proteins by chemical and physical agents will disrupt _______ and _____
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replication and metabolism
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What are two types of physical control?
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heat
direct flame |
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WHy is heat a good type of physical control?
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fast, reliable, cheap
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Is dry heat more or less effective than moist heat?
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less effective
think: stockton vs. boston |
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What kind of heat is required for powders or oils?
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dry heat
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direct flame leads to ___
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incineration
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Give an example of an organism that requires incineration.
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Bacillus anthracis (causes anthrax)
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What is thermal death time?
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the time it takes to kill a microbe at a given temperature
ex: TDT (thermal death time) for tubercle bacilli is 30'@58oC but only 2'@72oC |
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A hot air oven radiates ____heat at 160oC
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dry heat
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a hot air oven kills by ______ reactions (alters proteins) and ______
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oxidation reactions (alters proteins) and removal of water
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hot air ovens are used for powders, oils, glassware. It takes ___ hours to kill spores
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2
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What is good about the hot air oven?
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It does not corrode or erode
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Why is moist heat better than dry heat?
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water molecules conduct heat better than air
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What is the degree Celcius limit of boiling water?
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100 oC
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How does boiling water kill?
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kills by denaturing proteins (ex: egg cahnges color after cooking)
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Why is boiling water not considered a sterilization agent?
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no guarantee that spores are killed
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If you boil water for ten minutes, what is killed?
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vegetative cells
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If you boil water for 30 minutes, what is killed?
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protozoal cysts, fungal spores, large concentrations of hepatitis A virus
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If water is boiled 120 minutes or more, what is killed?
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bacterial spores (but some spores can survive boiling water for hours)
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Autoclave (121.5oC) requires _____minutes for sterilization of most vegetative cells and endospores
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15-30
An autoclave creates hot moist air under pressure up to 121.5oC. It kills most everything in 30 minutes |
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Is pasteurization sterilization?
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Pasteurization is NOT sterilization
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Pasteurization is ____ to high temperature to reduce microbial population and to increase shelf life
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brief exposure
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Pasteurization is brief exposure to high temperature to _____ and to ____
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reduce microbial population and to increase shelf life
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In pasteurization, what is not affected?
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spores
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pasteurization is aimed at destroying waht?
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most heat resistant organisms
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Pasteurization is aimed at destroying most heat resistant organisms. Name two of them
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Mycobacterium tuberculosis and Coxiella burnetii (agent of Q fever)
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What is LTLT?
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low temperature, long term pasteurization
30', 62.9oC |
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What is HTST?
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high temperature, short term
FLASH PASTEURIZATION 15s, 71.6oC |
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What is ultrapasteurization?
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like flash pasteurization but at an extreme
3s, 82oC |
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Hot Oil technique of destroying microbes is used for ___ minutes at ____oC
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60'
160oC |
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Hot Oil is used by some dentists and physicians for _____
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sterilization of metal instruments
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What is good about hot oil?
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it does not corrode or erode metal
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What is bad about hot oil?
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oil has to be cleaned off after treatment, contamination may be reintroduced
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filtration removes microorganisms by ____, _____, or _____
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screening, entrapment, or adsorption
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There are several types of filters. Name three
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organic filters
membrane HEPA organic filters are advantageous because the organic molecules of the filter attract organic components in microorganisms. It uses a substance called diatomaceous earth. This material contains the remains of marine algae known as diatoms. |
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The membrane filter consists of?
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cellulose acetate, nitrocellulose or
- (top) nylon membrane with E. coli (can keep E.coli out) - (bottom) polycarbonate w/ Leptospira *cellulose acetate, polycarbonate* |
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HEPA
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high efficiency particulate air filter
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HEPA removes ____% of particles larger than ____
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99.9%
0.3 um |
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What is the advantage of filters?
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can be put on a plate and counted
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What is the disadvantages of filters?
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expensive, time-consuming, often get clogged
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What are the disadvantages of membrane filters?
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- flammable (nylon membrane)
- physical limitations (mud --> get clogged) |
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UV light induces ___
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thymine dimers
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UV light induces thymine dimers. Mutations occur randomly, sometimes in important genes. It is good for ____
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surface sterilization
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When it comes to spores, gram ____ are less susceptible to UV light than gram _____
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positives
negatives |
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What are two forms of ionizing radiation?
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x-rays, gamma rays
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ionization radiation have a shorter wavelengths than UV light. IT forces electrons out of shells and creates
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ions
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ionizing radiation destroys ____
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nucleic acids, proteins
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ionizing radiation is used for ______
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heat-sensitive materials (pharmaceuticals, plastics)
* waves will kill pathogen but not chemical structure of drug |
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_____ is FDA approved for food use. It can kill Trichinella spiralis
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Cobalt-60
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Cobalt-60 is FDA approved for food use. It can kill ____
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Trichinella spiralis
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What bacterium can survive 1000x more radiation than humans?
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deinococcus radiodurans
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What do microwaves do?
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move water molecules
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With microwaves, other than heat or dessication, there is no ____
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no specific activity against microoranisms
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Laser is _____ by stimulated emission of radiation
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light amplification
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Laser is light amplification by _____
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stimulated emission of radiation
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With laser, concentrated light will destroy microbes instantly. WHat is the problem with laser?
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coverage is a problem
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Ultrasonic vibrations are microscopic bubbles caused by ____
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high frequency sound
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ultrasonic vibrations is also known as ____
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'cold boiling'
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In ultrasonic vibrations, the formation and implosion of bubbles is known as _____
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cavitation
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Some dentists and jewelers use ____
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cavitrons
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ultrasonic vibrations always requires ___
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liquid
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what happens with ultrasonic vibrations?
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1) high frequency sound waves cause microscopic bubbles to form in the fluid
2) As the bubbles collapse, shock waves are created in the fluid 3) alternating high and low-pressure areas impinge upon microorganisms and destroy them. |
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What are three preservation methods?
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-dessication
-salting or sugaring -low temperature |
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dessication. no water, no ___
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life
(bread vs. pretzels) |
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salting or sugaring has to do with ___
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osmotic pressure (water diffuses out with salt or sugar on the outside)
problematic: molds can tolerate high sugar (if make jams, jellies, find mold on top) |
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What is the problem with the sugaring technique of preservation?
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molds can tolerate high sugar
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low temperature lowers _____ of microorganisms
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metabolic rate
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low temperature reduces ___
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growth rate
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What is a problem with the preservation method of low temperature?
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some will remain alive at low temperature and start growing fast once out of low temperature
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